The present disclosure relates to an optical reading device for optically reading a document image and an image forming apparatus for forming an image on a sheet based on the document image.
An image forming apparatus for forming a copied image of a document image on a sheet includes an optical reading device for optically reading the document image. The optical reading device includes a scanning unit equipped with a light source for irradiating light for optical reading to a document placed on a document platen glass, a cable (flat cable), one end of which is connected to the scanning unit, and a housing for housing these. The scanning unit emits light toward the document platen glass while reciprocating along a predetermined scanning direction in the housing. An intermediate portion of the flat cable is curved and deformed as the scanning unit reciprocates.
The above housing is normally made of a frame structure of a sheet metal. The intermediate portion of the flat cable is in surface contact with the bottom plate of the housing, but the insulating coating of the flat cable is generally thin and electrical coupling (electrostatic coupling or electromagnetic coupling) may be formed between conductors of the flat cable and the bottom plate of the housing. In this case, if a contact state of the flat cable with the bottom plate changes due to a reciprocal movement of the scanning unit, a state of the electrical coupling becomes unstable. This causes the production of electromagnetic noise which affects the operation of the optical reading device or the image forming apparatus. To solve this problem, an insulating member is laid in an area where the flat cable is in surface contact with the bottom plate in a conventional technology.
However, in the conventional technology, the insulating member is interposed between the bottom plate of the housing and the flat cable and the electrical coupling is suppressed by the thickness of the insulating member. Accordingly, it is necessary to use a member with a considerable thickness or devise the shape of the insulating member, which causes a cost increase.
An object of the present disclosure is to provide an optical reading device and an image forming apparatus capable of simply suppressing unstable electrical coupling between a bottom plate of a housing and a cable.